The invention relates to a process for obtaining dextrose and dextrins from protein-containing starches.
The starting product constituting the starch is preferably a vegetable product such as potatoes, arrowroot or manioc (cassava) as well as grain feeds such as maize, sorghum, wheat, rice, rye or barley.
The complete hydrolysis of starch leads to dextrose. At present, principally two processes are in use for making dextrose from starch. One of the processes employs a pure acid hydrolysis. The other moves through a two-stage acid-enzyme process or a two-stage enzyme-enzyme process.
From the German published application No. 1,567,365 a process for making starch hydrolisates is known. In this case a syrup is obtained of a low dextrose value. The hydrolysis is effected in a two-step process with alpha-amylase.
A process for extracting starch from maize grit and the subsequent enzymatic saccharification is described by K. Kroyer in the publication Die Sterke, 10, 312 (1966).
In the German published application 2,417,639 a process is disclosed for liquefying corn starch. The starch there is mixed with water, a bacterial alpha-amylase and glucoamylase and is then processed at elevated temperatures. The German published application No. 1,717,126 likewise deals with a process for liquefying starch.
The shortcoming of all these prior art processes is that it is necessary to wash out to the extent possible all water-soluble components of the starch by swelling or elutriation with water in order to obtain a pure starch for the enzymatic hydrolysis and the recovery of a pure dextrose. This purification step causes substantial difficulties, particularly in case of wheat, rye and barley because of the grain size which is small compared with potatoe starch or corn starch and because of byproducts from the precipitation. A filtration in the classic sense of the word is not possible since what is involved is the separation of a solid from solids and a liquid.
In addition to the difficulties in obtaining a pure starch, further problems arise during the hydrolysis of the starch because of the unavoidable formation of byproducts during the degradation.
It is therefore an object of the present invention to provide for a process of obtaining dextrose and dextrins from protein-containing starches, for instance by enzymatic hydrolysis without requiring to use a pure starch as the starting product for the enzyme treatment.
Another object of the invention is to provide for a process whereby the main hydrolysis products, that is dextrose and dextrins can easily be separated from the protein and other accompanying substances.